[llvm] [LoopReduceMotion] Improve loop by extract reduction instruction (PR #179215)

[Luke Lau via llvm-commits]

================
@@ -1418,6 +1419,8 @@ void PassBuilder::addVectorPasses(OptimizationLevel Level,
   }
   // Enhance/cleanup vector code.
   FPM.addPass(VectorCombinePass());
+  // Try to sink ReduceCall out of loop
+  FPM.addPass(LoopReduceMotionPass());
----------------
lukel97 wrote:

I haven't tried this but if you wanted to make this a loop pass it would probably look like:

```suggestion
    LoopPassManager LPM;
    LPM.addPass(LoopReductionMotionPass());
    FPM.addPass(
        createFunctionToLoopPassAdaptor(std::move(LPM)));
```

https://github.com/llvm/llvm-project/pull/179215